1,720,978 research outputs found
Design optimization of large-scale structures with advanced meta-heuristic methods
Full text linkMetaheuristic algorithms nowadays represent the standard approach to engineering optimization. A very challenging field is large scale structural optimization entailing hundreds of design variables and thousands of nonlinear constraints on element stresses and nodal displacements. However, a very few studies documented the use of metaheuristic algorithms in large scale structural optimization. In order to fill this gap, an enhanced hybrid harmony search (HS) algorithm for weight minimization of large scale truss structures is presented in this PhD dissertation. The new algorithm, Large Scale Structural Optimization - Hybrid Harmony Search JAYA (LSSO-HHSJA), developed here combines a well established method like HS with a very recent method like JAYA, which has however the simplest and inherently most powerful search engine amongst metaheuristic optimizers. All stages of LSSO-HHSJA are aimed at reducing the number of structural analyses required in large scale structural optimization. The basic idea is to move along descent directions to generate new trial designs: directly through the use of gradient information in the HS phase, indirectly by correcting trial designs with JA-based operators that push search towards the best design currently stored in the population or the best design included in some local neighborhood of the currently analyzed trial design. The proposed algorithm is tested in three large scale weight minimization problems of truss structures. Optimization results obtained for the three benchmark examples with up to 280 sizing variables and 37374 nonlinear constraints prove the efficiency of the proposed LSSO-HHSJA algorithm, which is very competive with other HS and JAYA variants as well as with commercial gradient-based optimizers. The possibility of using the same hybridization strategy for another metaheuristic algorithm such as Big Bang-Big Crunch is also investigated by solving two highly nonlinear design problems including up to 84 variables, (i) shape optimization of a concrete dam and (ii) discrete layout optimization of a planar steel frame, to prove the feasibility of the proposed approach
Distribution and chemistry (Fe, Zn, Pb, Cu, Cd, Chlorophyll a) of suspended particulate matter in Strait of Magellan: Austral Spring 1989
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
DEMO Fusion Power Plant: Preliminary Sizing Analysis of Power System
No full textEU-DEMO is a European project for the design and construction of the first nuclear reactor able to produce electrical energy thanks to thermonuclear fusion reactions. The electrical power system of this facility is particular demanding for several reasons. First, the electrical power required to operate DEMO is expected to be huge, especially in comparison to a conventional nuclear plant. Moreover, the operations are intrinsically intermittent, thus introducing specific problems in terms of energy balance and grid stability. This paper deals with a first preliminary study about the sizing and the design of the DEMO internal electrical power system, with a specific focus on the steady-state loads necessary to operate the plant. The design results are obtained and verified through a model for power flow analysis, implemented in DIgSILENT PowerFactory
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